title: Surface diffusive motion in a periodic and asymmetric potential.
abstract: 9,10-Dithioanthracene adsorbed on Cu(111) diffuses exclusively along the high-symmetry axis of the molecule-substrate system. Further reduction of the symmetry of the system by asymmetric methylation does not reduce the symmetry of the motion although it has a substantial effect on the diffusion rate (100-fold reduction) and renders the diffusion barrier asymmetric. This is in contrast to the behavior expected of a classical particle, and it provides a direct single-molecule-scale vista on the validity of The Principle of Microscopic Reversibility first formulated by Tolman in 1924, which despite its fundamental role has attracted little visualization.
authors.affiliation: Pierce Hall, University of California, Riverside, California 92521, USA.
authors.forename: Greg
authors.initials: G
authors.lastname: Pawin
authors.forename: Kin L
authors.initials: KL
authors.lastname: Wong
authors.forename: Ki-Young
authors.initials: KY
authors.lastname: Kwon
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Frisbee
authors.forename: Talat S
authors.initials: TS
authors.lastname: Rahman
authors.forename: Ludwig
authors.initials: L
authors.lastname: Bartels